Polyvinyl alcohol-stabilized ethanol formamide composition



Patented Nov. 18, 1947 POLYVINYL ALCOHOL-STABILIZED ETHA- NOL FORMAMIDECOMPOSITION Charles Arthur Porter, Belleville, and Reuben Fershko,Newark, N. 1., assign'ors to Resistoflcx Corporation, Belleville, N. J.,a corporation of New York No Drawing. Application January 3, 1946;

Serial No. 638,916

6 Claims. (Cl. 260-36) This invention relates to the stabilization ofethanol formamide and to polyvinyl alcohol compositions containing thestabilized product.

The stabilized ethanol formamide product is the subject matter of ourapplication Ser. No. 722,754, filed January 17, 1947, as a divisionhereof. The claims herein are directed to polyvinyl alcohol compositionscontaining the stabilized product.

Ethanol formamide (HCO-NH-CzH4-OH), as commercially produced, isinitially a colorless neutral liquid. It is useful as a plasticizer orsoftening agent, especially in polyvinyl alcohol compositions.

During storage at ordinary room temperatures it has been found thatethanol formamid shows indications of decomposition in becomingprogressively more discolored and alkaline. Heat accelerates thisdecomposition. When held at 130 C. for 48 hours there is pronouncedcolor change, the substance darkening, precipitate is formed and thematerial becomes alkaline.

Polyvinyl alcohol compositions containing ethanol formamide asplasticizer are frequently subjected to temperatures as high as 130 C.as,

for example, in flexible oil lines used on gasoline and Diesel engines.Under such circumstances it is disadvantageous to have a plasticizerundergoing decomposition as it resultsin loss of flexibility.

The objects of this invention are to stabilize ethanol formamide and toprovide improved polyvinyl alcohol compositions plasticized with thestabilized product.

It has been discovered that the decomposition of ethanol formamide canbe prevented or greatly retarded by adding thereto formic acid or aceticacid or their esters with glycerol and glycols.

Formlc acid has been found to have the most pronounced stabilizingeffect and to be efiective for the longest time. Acetic acid is aneffective stabilizer but its efficacy does not endure for as long atelevated temperatures. The efiectiveness of the glycerol and glycolesters of these acids is believed to be due to the liberation of freeacid when heated or subjected to hydrolyzing conditions. Where theseesters are used as plasticizers .2 is hydrolyzed to produce formic acid.which acts to stabilize the ethanol formamide, it also yields glycolwhich is in itself a plasticizer for poly- 'vinyl alcohol.

Comparisons made between treated and untreated ethanol formamide, showedthe following advantages. Untreated ethanol formamide heated at 130 C.for 48 hours suffered pro-- nounced decomposition as indicated by colorchange, the production of precipitate and increased alkalinity. Ethanolformamide containing 5% of formic acid showed no decomposition after 200hours under the same conditions. When 5% of acetic acid (glacial),glycol diacetate, diacetln or triacetin was incorporated in ethanolformamide, no decomposition was evident after hours of heating at C. ascompared with pronounced decomposition in 48 hours of the untreatedmaterial. Only after 100 hours was slight decomposition noticed. Glycoldiformate had a comparable stabilizing effect.

The amount of stabilizer to be used will depend on the impurities whichmay be present in the ethanol formamide. The impurities are known to bealkaline in nature and there must be sufiicient acid to effectneutralization. We believe that theimpurities, which result from and inturn may promote the decomposition, are probably amines and that theacid reacts with them to form salts which on subsequent heating wouldyield amides having no tendency to cause any decomposition of theethanol formamide. We do not wish. however, to be limited by thistheory.

It has been found that from 3% to 5% of the stabilizing agent isgenerally sufficlent and no undesirable effects have been observed inusing as much as 20%, where the stabilized product was used as aplasticizer for polyvinyl alcohol. The only apparent requirement withrespect to quantity is to use enough to secure the stabilizing effect. I

Forinic acid (85%) was mixed with ethanol formamide in the weight ratioof 5 to 95 and heated in an open flask at 130 C. for 24 hours. Initiallythere was a strong odor of formic acid which gradually disappeared, thefinal stabilized product being completely odorless. Since thetemperature was considerably above the boiling point of formic acid, itis evident that no free acid could be present at the end of the period.yet the ethanol formamide remained stable and showed no other change inits properties. It has been found further that such treatment, inaddition to rendering ethanol formamide stable, will 3 also removeslight discoloration which may exist before the stabilizer is added.

The stabilized ethanol formamide Just described was incorporated asplasticizer in the following polyvinyl alcohol composition, suitable forthe formation of molded sheets:

Parts Polyvinyl alcohol (completely saponifled) 50 Water 20 Glycerol 15Ethanol formamide (stabilized) 20 The molded product showed improvedretention of flexibility at elevated temperature over products of thesame formula in which unstabilized ethanol formamide was used.

It is to be understood, however, that it is not necessary to remove freeformic acid or other stabilizer, as was done above, before using thetreated ethanol formamide as a plasticizer. It may be so usedimmediately after the addition of the stabilizer or the stabilizer maybe added to the composition with the other ingredients.

The foregoing specific description is to be construed as merelyillustrative of the invention, which is defined in the claims.

What is claimed is:

1. A molding composition comprising polyvinyl alcohol, ethanolformamide, and formic acid.

2. A molding composition comprising polyvinyl alcohol, ethanolformamide, and acetic acid.

3. A molding composition comprising polyvinyl alcohol, ethanolformamide, and glycol diformate.

4. A polyvinyl alcohol composition containing as a plasticizer ethanolformamide stabilized by the addition of a substance selected from thegroup consisting of formic acid, acetic acid and the formic and aceticacid esters of glycerol and glycol.

5. A composition for use in forming shaped articles by means of heatand'pressure comprising polyvinyl alcohol, ethanol formamide and aREFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,967,388 Ziegler July 24, 19342,250,664 Watkins July 29, 1941

